This is supposed to give only the bigger picture of how things work so lots of information packed in to very little text.
If you notice that something is missing or you totally disagree with something, just let me know.
Enjoy.

Interesting that you mention overlapping elements, I think those are the hardest to do intuitively. Especially in speed painting....
Another thing that comes to my mind is scale, big proportions versus smaller and to make them work in a composition. There's a rule for that in decorative painting, there one speaks about a rule of thirds; to get variety there's three different brush sizes and etc.